(Proveit.txt)
A HISTORY OF THE ORIGIN OF THE BOX-CAMERA THEORY OF THE EYE
A QUESTION CONCERNING THE NATURE OF PROOF
Reference: "Introduction to Physiological Optics", by James
Southall
I have often hear the words, "prove it", with respect to the
fact that the fundamental eye can have a negative refractive
state.
Since the "it" is never described, it follows that no one can
ever "prove it".
But if the requirement is to prove that the eye is an
auto-focused camera versus the box-camera concept, then proof is
possible.
I wrote my book so that you could help your own daughter
avoid nearsightedness. I know you want to help others but --
regardless of proof -- I do not think the general public will
understand what must be done.
Dr. Jacob Raphaelson went through this 100 years ago, as
described in, "The Printer's Son". The public wants their distant
vision sharpened instantly, and expects this of you. Anything
beyond that point they will reject -- unless they are very
motivated and intelligent about this difficult situation. It is
very clear that the person who desires prevention must have strong
motivation and support from you if the person plans to use the
plus lens effectively.
In my opinion, your work with the public is very difficult
because the public is not logical, and not consistent in what they
expect. Unless they have the motivation, they will not push hard
in the proper use of a plus lens. A professional pilot, who looks
at his own eye chart and sees the results as they develop will be
your best candidate for effective prevention.
The public demands immediate results and does not listen to
explanations. They will quit an effort if their is the slightest
problem, or if some other ophthalmologist or optometrist uses
"scare" tactics against them. If this happens, they will quit the
effort and blame you for anything that might happen with their
eyes. There is no incentive to attempt to help most people -- and
both you and I understand that truth.
The health profession has no choice except to apply a minus
lens and (with a few exceptions) suggests that anyone who asks
deeper questions about these issues must be "not-scientific".
I can accept this as the reality of medicine. They should
say "non-medical", rather than "not-scientific".
In science, you pay attention to direct objective
measurements. This is not quite true in optometry -- as I
described above.
Tragically, this unfortunate situation has continued since
its inception 400 years ago. The theory of the eye began this
way:
1. The lens-developers dealing with the public found a plus lens
that would sharpen near vision -- when you reached old-age.
2. In addition, they found that young people with slightly blurry
distant vision, could clear their distant vision with a minus
lens.
The theory of using a lens on the public is based on the
above understanding of responsibility and resulting direct action.
There has been very little improvement in this concept of the eye.
Around 1600 Johan Kepler (Astronomer) began developing a
pure-refractive theory of the eye. This was good work, but
assumed that you could "freeze" the eye and make all your
measurements based on the box-camera concept. This idea never
attempted to analyze the eye's dynamic behavior at all -- only the
refractive properties of an intellectually frozen eye.
This analysis this approach was good, so the fact that the
eye is not frozen was forgotten. Kepler's analysis could be used
to support Items 1 and 2. For this reason the "frozen eye" theory
was accepted as a medical theory -- and anyone who challenged the
concept concerning the bad results of item 2 were told that
Kepler's theory was "proven" and that the natural eye is a rigid
box cameras.
Kepler's theory was further refined and re-published in 1858
by two ophthalmologists, Dr. Donders and Dr. Helmholtz.
They accepted Kepler's frozen-eye concept, and added further
assumptions.
1. They assumed that a focal state of exactly zero could be
considered normal. Donders invented the word emmetropia to
describe this idealization of the "frozen" eye.
2. They assumed that any focal state other than exactly zero must
be a defect, or "refractive error". They invented the word
"ametropia" to describe both positive and negative focal
states of all normal eyes.
Don't get me wrong at this point. These were great men in
medicine at that time. But they continued the academic assumption
of Kepler, that you could "freeze" the eye and do a pure
refractive analysis. They also assumed that you could translate a
relative focal state into an absolute dimensions. (i.e., they
assumed that if the eye had a focal state of zero, it must have an
exact length of 24.38 mm. In fact no relationship has ever been
established.)
By doing this, they thought that they made the Kepler's
theory into proof that the eye was "too long", when the natural
eye simply had a normal but undesired negative focal state.
This box-camera theory made the use of a plus or minus lens
seem more systematic, although it requires a belief that the eye
is defective if it has a negative or positive focal state. (i.e.,
if your eyes have a focal state that is not zero, you are
suffering from "stress and strain" because the eye is too long or
too short. The reasoning here is circular, because it is not
proven that a focal state of zero corresponds to a exact length.
It is only an assumption that you can convert relative
measurements into absolute dimensions.)
In any event, this theory makes all eyes defective by
definition -- a thesis of doubtful validity.
Why should we object to Kepler's theory, which became the a
theory of practice? As a theory that allows refractive analysis
of an idealized eye it is excellent. As a theory of the eye that
reproduces the actual motion and change of focal state of the
natural eye -- it is not accurate.
Kepler's pure-refractive theory was correct, but the
assumptions of the follow-on (Donders-Helmholtz) theory are not
accurate or correct.
In the light of experimental data developed in the last 50
years we should begin developing a better conceptual model of the
eye's dynamic behavior.
The experimental facts demonstrate that all eyes change their
focal state as the visual environment is changed. By reference to
the facts, the eye is established to be a well designed
auto-focused camera. (i.e., you can make ALL eyes nearsighted by
forced wearing of a minus lens.)
The type of data needed to demonstrate this truth was not
available in 1860. So the original conception should undergo
evolution to account for these recently developed facts. But in
fact, the operative reasons for using a plus or minus lens have
not change since their original inception -- 400 years ago. Thus
the "theory of the eye" is driven by expediency, and not by
objective scientific facts -- in my humble opinion.
Science is based on objective facts. We should be able to
recognize that there is a problem with expanding Kepler's theory,
beyond its original intended scope. He did an excellent
refractive analysis. He did not intend that we believe that all
eyes are rigid box cameras that are defective because they have
focal states other than zero.
We suggest that the natural eye is an auto-focused camera,
and that, for this reason, the natural eyes must change its focal
state (which you measure) as you change the visual environment
(which you control). Since we are using neutral language to
describe this situation, it follows that experimental conformation
(that all eyes are auto-focused cameras) will be straight forward.
The nature of this type of experiment can hardly be argued.
This means that the evolution-designed eye can have both
negative and positive focal states, and not be defective.
In fact, the measured focal state of your eyes is directly
dependent on your accommodation level -- in diopters.
Obviously, if you work for long hours, your normal eyes are
going to develop a negative focal state. This is perfectly normal
and an expected for an auto-focus camera.
The Helmholtz-Donders theory, and its required assumption has
never been objectively tested -- as stated by Dr. William H.
Bates. This means, that the box-camera picture of the eye is
misleading at best. At worst, it blinds us to a potential method
of preventing the development of nearsightedness by aggressive use
of a plus lens.
Sincerely,
Otis Brown